1. Field of the Invention
This invention relates generally to apparatus for detecting when a door has not been closed and more particularly, but not by way of limitation, to apparatus for determining when a door has been left open for a predetermined period of time.
2. Description of the Prior Art
In various situations it is important to know whether a door has been closed within a certain amount of time. For example, in the restaurant industry and other food-handling businesses wherein the cold storage of meats and produce is imperative for food quality and health reasons, it is important that the door to the cold storage area be closed whenever someone is neither entering nor exiting therefrom. In many instances employees enter the storage area, such as a walk-in freezer, to obtain necessary food, but upon exiting the area they fail to properly close the door. Such neglect leads to wasteful energy consumption to overcome the loss of refrigeration through the open door and also leads to spoiled goods when adequate refrigeration cannot be maintained. Therefore, in these situations it is vital to provide a means for alerting those within the vicinity of the door that the door has not been closed after it has been left open for a predertermined period of time.
There have been certain proposals for devices which detect when a door, window, or the like has been initially opened. An example of this is a common burglar alarm. However, we do not believe that any such previous proposals disclose, either singly or in combination, the apparatus of the present invention which detects the non-closing of a door after it has remained open for a period of time.